Wax-substituted diaryl dithiophosphoric acids and salts thereof



Patented July 12, 1949 UNITED STATES PATENT OFFICE WAX-SUBSTITUTED DIARYL DITHIOPHOS- PHORIC ACIDS AND SALTS THEREOF No Drawing. Application April 5, 1945, Serial No. 586,835

13 Claims.

This invention has to do with new chemical compounds or reaction products which may be generally designated as wax-substituted diaryl dithiophosphoric acids and salts thereof.

The present invention is predicated upon the discovery that the compounds or reaction products contemplated herein when blended with a viscous mineral oil fraction such as hydrocarbon lubricating oil, will improve various properties of the oil. For example, these compounds or reaction products will inhibit oxidation of the oil, thereby retarding the formation of sludge and acidic products. They also retard changes in viscosity, in the oil, with temperature change during use. In addition, they are characterized by the ability to depress the pour point of oils.

It is to be understood, however, that the present invention is not concerned with mineral oil compositions, such compositions forming the subject matter of my copending application, Serial No. 528,783, filed March 30, 1944, now matured into U. S. Patent No. 2,410,650, issued November 5, 1946, of which the present application is a continuation-in-part, the latter application, in turn, being a continuation-in-part of application Serial No. 390,586, filed April 26, 1941, now abandoned.

It is also to be understood that the use of the compounds or reaction products contemplated herein is not confined to the improvement of mineral oils. For example, they may be used as cutting oils, rubber accelerators, extreme pressure lubricants and as intermediates in the production of other chemical compositions. Numerous other uses and applications of these compounds or reaction products will be readily apparent to those skilled in the art from the description of their composition and typical methods for preparing them, as provided hereinafter.

The class of compounds or reaction products contemplated herein are organic compounds containing sulfur, phosphorus and metal in chemical combination or a mixture thereof predominantly comprised of compounds obtained by reacting phosphorus penta-sulfide with an alkyl-substitutcd phenol and then introducing metal into the product thus obtained by reaction with a metal hydroxide or the like. These compounds or reaction products contain a hydrocarbon group or groups of a character which will impart oilmiscibility or oil-solubility to the compound or reaction product.

The present invention contemplates compounds of the class described wherein the oil-solubilizing action is obtained from an alkylated aryl nucleus which, in addition to oil-solubility imparts pourdepressant properties to the compound or reaction product. The pour-depressant property is obtained by employing an aryl nucleus which is substituted with relatively long-chain alkyl groups, such as those characterizing paraffin wax (predominantly alkyl groups of at least twenty carbon atoms).

A compound or reaction product of the type contemplated herein may be broadly described as an oil-miscible metal salt of a thio acid of phosphorus or, more specifically, as a metal salt of a partial ester of a thio acid of phosphorus, obtained by reacting PzSs with a compound having the general formula ROH wherein R represents an alkaryl oil solubilizing hydrocarbon group of the type described above and then reacting the product thus obtained with a reactive metal compound. Although, as aforesaid, we do not wish to be bound by any theory of reaction or formula of the product, it does appear that under certain conditions of reaction and reactants the ultimate products obtained are the metal salts of wax-substituted diaryl dithiophosphoric acid, the general structural formula oiwhich may be expressed as follows:

wherein R1; represents at least one alkyl group having at least twenty carbon atoms or an alkyl group corresponding to the aliphatic hydrocarpoly-cyclic and, as aforesaid-"the' alkyl' substitueht thereon should correspond to an alkyl" group of sufiiciently high moleculan weig-ht. to impart to the compound pour point-depressingand-vise cosity index-improving action in addition to oil miscibility. For alkyl substituents, that will impart these properties, particularpreference is given to alkyl groups of at least twenty carbon atoms.

As to the metallic constituent M, it appears .that any metal may be: used. Thealkaline earth metals are preferred, :with. particular. preference given to barium. Other representative. metals which may be usedarezinc, tin,' -aluminum, co- -balt, nickel,. chromium, the alkali'metals, etc.

-Asaforesaid, the reactionrproducts. contem-I plated herein as typified by the metal'saltsof. the partial. esters. of dithiophosphoric. .acidmay be preparediby first forming the correspondingpartial ester of dithiophosphoric acid byiany. known method,- such asthatdescribed by. PI S; Peschimuka.-(J. Russ..P.hys.- Cheml Soc, 56,.11 (1925); (Chem. :Ab., 19,-280'8) ,-wherein phosphorus pent'a: sulfide. isreacted with. an alcohoLand then reacting the partially. esterified .-acid thus formed with ametallic. hydroxide to form themetal salt of-thepartial-ester ofdithiophosphoric acid. The reactions involved can probably .be expressed: by the. following equations, ..although,. as aforesaid, we do notwishto bev bound .by anytheoryvof reaction.

EXAMPLE. 1'

METAL SALTS 'oF' DEALKARYII' Dirm'ornosenoxr'c' v A'om Wax substituted phenol iwas first prepared by the Friedel-Crafts condensation of chlorinated parafiln wax (16 per cent chlorine content) with phenol in the ratio of 1 molecular part phenol to 3 atomic parts chlorine-in the chlorwax. The wax-substituted diphenyl dithiophosphoric acid was obtained by making a reaction mixture of 100 grams of the wax-phenol, 8.1 grams of P285, and 300 grams of mineral oil .o'f saybolt viscosity of 67 seconds at 210 F. This mixture was heated at 100 C. until the evolution OfHzS had substantially stopped (about 15 or-.20 hours). The clear solution Was then. blown with a stream..0f nitrogen to remove entrainedHS; to obtain the product which, for purposes of identification herein we may refer to as wax-substituted"diphenyl di- 4 thiophosphoric acid (3-16) in approximately 25 per cent mineral oil blend.

The stannous salt of wax-substituted diphenyl dithiophosphoric acid was obtained by dissolving 100. grams of the acid product obtained by the procedure last described i above: (dissolved in 300 grams of mineral oil) in cc. of butyl alcohol,

adding 1.5 grams of metallic sodium, and heating the mixture at the reflux temperature of the alcohol until the sodium? was all reacted. A butyl alcohol solution of stannous chloride (6.2 grams of SnClz) was then added and the mixture slowly heated to 150 C. while the alcohol was distill-ed 011- The mixture was then cooled, diluted with benzol and filtered through a filter-aid clay to r emovefNaCl',': after which the solvent Was distilled ofi'to' obtain the finished product.

Thebarium salt of wax-substituted diphenyl dithiophosphoric acid was prepared by forming a reaction mixture consisting of 100 grams of the wax-substituted dipheny-l dithiophosphori'ca'cid in 3'0'0 grams of 'min'era'l oil'; 1'1'gramsof and 100 cc. ofbenzol. The mixture-was: gradually heatedt'o 150"C5, the ben'zol a'nd ithe .water. formed in-the reaction therebybeing distilled-01f. After the reaction mixture 'was cool'ed,.it:was diluted with benzol; filtered" through a filter-aidaclay to remove unwanted Ba(OH:) 2:8H2O; andithe solvent was distilled off toobtaini the finished product.v

Typical metal salts ofipartial: esters: of dithioe phosphoric acid which havetbeensynthesiz-ed' and demonstrated. to be effective addition agents: for hydrocarbon oils of' thetypeiused': in; lubricants and the like are thefollowing:

stannous. di(wax-phenyl) dithioph'osph'ate Barium di(wax-pheny1) .dithiophosphate The following examples-will illustrate the effectiveness (if the compounds: contemplated herein to stabilize and improvethe-various:properties of various viscous hydrocarbonoilsz.

I Cormoszon- TEsr "The c'orrosibn-inhibiting:action of." thesecompoun'ds was demonstrated in: the so-called; catalyzed Underwood" oxidation" test; which is described in a' pamphlet-g.datedvAugust-'1, 1938; of the Research Laboratories Divisionof the General Motors Corporation; entitled UnderwoodzOxidatio'n-"Testing' Apparatus. The following results were obtained'byusing- 'a motoroil of 2-10 seconds Saybolt viscosity at F. with the addition r of sufficient. iron naphthenate to be equivalent to 0.01rper'cent-ironoxide to act as aca-talyst. Bearings containing a cadmium-nickel surface were used and the-*Mg. loss inmbearing weight and: the acidity of the oil (N. N. value -weredetermined after. five hours of :test.

Pomr DEPREssANr. AND-IVL5I;-.1MPR0VE1\EENT 'As' aforesaid, the so-called wax -sub'stit'uted compoundshavefthe properties of acting as pour point-depressants-'- and viscosity index-'improver'si These properties are demonstrated by the results set forth in Tables II and III below showing pour point-depressing and V. I. results, respectively, on typical motor oils with and without the addition agent.

Table II A. S. 'l. M. Four Points Compound Blended with Motor Oil of Blends 67 Sec. Saybolt Viscosity at 210 F.

F. F. F. None +20 Barium salt of wax-substituted diphenyl dithiophosphoric acid (3-16) 1O -20 Table III Kinenisatic Vis- Compound Blended with cos] y Lubricating Oil I Per cent None 0 29. 56 4. 72 76. 7 Wax-substituted diphenyl dithiophosphoric acid (346).". 1 32. 28 5. 04 86.0 Barium salt of wax-substituted diphenyl dithio phosphoric acid (3-16) 1 33. 06 5. 89. 6

The parenthetical expression (3-16) used in Tables I, II and III and in Example 1 above indicates the number of atomic proportions (3) of chlorine in the chlorwax reacted with 1 molecular part of phenol and the percentage (16) of chlorine in the chlorwax used in this reaction from which the wax phenol was obtained. This wax phenol (3-16) provides the wax-substituted phenyl substituents in the salts disclosed herein, as described in Example 1.

The compounds or reaction products contemplated herein may be used in various amounts depending upon the character of the oil and the severity of the conditions under which it is to be used. In general it appears that satisfactory improvement may be obtained with amounts ranging from about 0.01 per cent to about 5.0 per cent.

It is to be understood that While I have herein described certain specific compounds and procedures to illustrate the invention, such specific examples are illustrative only and the invention embraces within its scope such changes and modifications as fairly come within the spirit of the appended claims.

I claim:

1. Compounds having the general formula RO/ s in which R is a paraffin wax-substituted aryl radical, said parafifin wax substituent containing at least 20 carbon atoms, M is a member of the group consisting of hydrogen and basic saltforming groups, and n is the valence of hydrogen or the basic salt-forming group.

2. Compounds having the general formula R-O sin which R is a paraffin wax-substituted aryl radical, said paraffin wax substituent containing at least 20 carbon atoms, and M is an alkaline earth metal.

3. Compounds having'thegeneral formula in which R is a parafiin wax-substituted aryl radical, said parafiin wax substituent containing at least 20 carbon atoms.

4. Compounds having the general formula in which R is a parafiin wax substituted phenyl radical, said paraifin wax substituent containing at least 20 carbon atoms, and M is an alkaline earth metal.

5. Compounds having the general formula R-O /S RO R in which R is a parafiin wax-substituted-phenyl radical said wax substituent containing at least 20 carbon atoms.

6. As a new composition of matter, an oilmiscible metal salt of a substituted thio acid of phosphorus having the general formula wherein Rn represents at least 1 paraffin wax group containing at least 20 carbon atoms, and M represents the hydrogen equivalent of a metal.

7. As anew composition of matter, an oilmiscible metal salt of a paraflin wax-phenylsubstituted thio acid of phosphorus, said paraffin wax substituent containing at least 20 carbon atoms.

8. As a new composition of matter, a metal salt of a paraffin Wax-substituted diaryl dithiophosphoric acid, said paraffin-wax substituent containing at least 20 carbon atoms.

9. As a new composition of matter, an alkaline earth metal salt of a paraflin wax-substituted diaryl dithiophosphoric acid, said paraffin Wax substituent containing at least 20 carbon atoms.

10. As a new composition of matter, the barium salt of di (parafiin wax phenyl) dithiophosphoric acid, said paraffin wax substituent containing at least 20 carbon atoms.

11. As a new composition of matter, an oilmiscible zinc salt of an acidic reaction product obtained by reacting P285 with a compound having the formula Rn OH wherein Rn represents at least 1 paraflin wax group containing at least 20 carbon atoms.

12. As a new composition of matter, an oilmiscible stannous salt of an acidic reaction prod,

memos! uct5obtahieisbyrreactlnm'msaswith a:- compound having the formula whereim'Rn -representseat least 1 paraffin wax group containing at least 20; carbon: atoms.

13. cfompourids havingi; the generalformula The following; references are of record in. the filer of thispatent-z UNITED STATES PATENTS Number Name" Date 1,867,631 Romieux July 19, 1932 1,893;0-18' Christman Jan. 3, 1933 1,939,951. Buchanan! Dec. 19,1 1933 2,177,923 Berger Oct. 31, 1939 2,188,943 Evers Feb. 6, 1940 2 205337 Berger June 18, 1940 1 2,206,284 Jayne July 2,1940 2,246,059 Moran 'June117,' 1941 2,252,984 Rutherford Aug. 19, 1941 2,252,985 Rutherford Aug. 19, 1941 2,365,938 Cook Dec. 26, 1944 

